This invention relates to gas flow measuring apparatus, such as an apparatus for measuring the amount of air flow to an engine.
In the past, an apparatus has been proposed which comprises a flow measuring pipe positioned in the intake pipe of an engine and an electric heater and temperature dependent resistors which are disposed in the flow measuring pipe, whereby the flow rate of air (the gas to be measured) is measured from their output signals.
While this apparatus has the advantage of ensuring accurate flow measurement with a compact and simple construction, there is a disadvantage that due to lack of due regard to the stretching of the resistance wires forming the electric heater and the temperature dependent resistors, the elements are affected by a small variation in the heat distribution and this causes the measuring accuracy to vary in accordance with the flow rate of air.